Abstract:
The river streamflows analyses can be successfully used in water resource planning and management, depending on the needs of the wide range users. It is possible to use these applications in several general directions: as informal, qualitative guidance for water managers, stakeholders and decision makers and prediction about long-term drought variability; for quantitative assessments of longterm hydrologic variability and assessment the severity and duration of drought cycles; as direct inputs into hydrologic models of a water system, etc. The longterm oscillations of the river streamflows are influenced mainly by the solar activity and climate interaction, whose variations often consist of synchronous cycles. The intrinsic oscillations of Danube and Don streamflows are determined by the recently created autoregressive method ARIST. These oscillations are compared with the intrinsic oscillations of solar and climate indices and mean Black Sea level variations. Conclusions about the use of intrinsic oscillations in floods or drought prediction are made.